Cervical Artificial Disc Replacement Versus Fusion for Cervical Degenerative Disc Disease: A Health Technology Assessment

Abstract

Background: Cervical degenerative disc disease is a multifactorial condition that begins with deterioration of the intervertebral disc and results in further degeneration within the spine involving the facet joints and ligaments. This health technology assessment examined the effectiveness, safety, durability, and cost-effectiveness of cervical artificial disc replacement (C-ADR) versus fusion for treating cervical degenerative disc disease.

Methods: We performed a systematic literature search of the clinical evidence comparing C-ADR with fusion. We assessed the risk of bias in each study and the quality of the body of evidence according to the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) Working Group criteria. We performed a systematic review of the economic literature and assessed the cost-effectiveness of C-ADR compared with fusion. We also estimated the budget impact of publicly funding C-ADR in Ontario over the next 5 years. To contextualize the potential value of C-ADR, we spoke with people with cervical degenerative disc disease.

Results: Eight studies of C-ADR for one-level cervical degenerative disc disease and two studies of C-ADR for two-level disease satisfied the criterion of statistical noninferiority compared with fusion on the primary outcome of 2-year overall treatment success (GRADE: Moderate). In two studies of C-ADR for two-level disease, C-ADR was statistically superior to fusion surgery for the same primary outcome (GRADE: Moderate). C-ADR was also noninferior to fusion for perioperative outcomes (e.g., operative time, blood loss), patient satisfaction, and health-related quality of life (GRADE: Moderate). C-ADR was superior to fusion for recovery and return to work, had higher technical success, and had lower rates of re-operation at the index site (GRADE: Moderate). C-ADR also maintained motion at the index-treated cervical level (GRADE: Moderate), but evidence was insufficient to determine if adjacent-level surgery rates differed between C-ADR and fusion. Current evidence is also insufficient to determine the long-term durability of C-ADR.The primary economic analysis shows that C-ADR is likely to be cost-effective compared with fusion for both one-level ($11,607/quality-adjusted life-year [QALY]) and two-level ($16,782/QALY) degeneration. Various sensitivity and scenario analyses confirm the robustness of the results. The current uptake for one-level and two-level C-ADR in Ontario is about 8% of the total eligible. For one-level involvement, the estimated net budget impact increases from $7,243 (18 procedures) in the first year to $395,623 (196 procedures) in the fifth year following public funding, for a total budget impact over 5 years of $916,326. For two-level involvement, the corresponding values are $5,460 (7 procedures) in the first year and $283,689 (76 procedures) in the fifth year, for an estimated total budget impact of $705,628 over 5 years.People with cervical degenerative disc disease reported that symptoms of pain and numbness can have a negative impact on their quality of life. People with whom we spoke had tried a variety of treatments with minor success; surgery was perceived as the most effective and permanent solution. Those who had undergone C-ADR spoke positively of its impact on their quality of life and ability to move their neck after surgery. The limited availability of C-ADR in Ontario was viewed as a barrier to receiving this treatment.

Conclusions: For carefully selected patients with cervical degenerative disc disease, C-ADR provides patient-important and statistically significant reductions in pain and disability. Further, unlike fusion, C-ADR allows people to maintain relatively normal cervical spine motion.Compared with fusion, C-ADR appears to represent good value for money for adults with one-level cervical degenerative disc disease ($11,607/QALY) and for adults with two-level disease ($16,782/QALY). In Ontario, publicly funding C-ADR could result in total additional costs of $916,326 for one-level procedures and $705,628 for two-level procedures over the next 5 years.People with whom we spoke who had undergone C-ADR surgery spoke positively of its impact on their quality of life and ability to move their neck after surgery. The limited availability of C-ADR in Ontario was viewed as a barrier to receiving this treatment.

Figure 1:. PRISMA Flow Diagram—Clinical Search Strategy

Figure 2:. Graphical Display of Two-Year Mean OTS for One-level Disease—Proportion of C-ADR Versus Fusion OTS and 10% Noninferiority Margin

Figure 3:. PRISMA Flow Diagram—Economic Search Strategy

Figure 4:. Decision Tree and Markov Models for One-Level and Two-Level C-ADR Versus Fusion

Figure 5:. Tornado Diagram for One-Level Surgery

Figure 6:. Tornado Diagram for Two-Level Surgery

Figure 7:. Incremental Cost-Effectiveness Plane for C-ADR Versus Fusion With a Willingness-to-Pay of $50,000 per QALY for One-Level Cervical Degenerative Disc Disease

Figure 8:. Incremental Cost-Effectiveness Plane for C-ADR Versus Fusion With a Willingness-to-Pay of $50,000 per QALY for Two-Level Cervical Degenerative Disc Disease

Figure 9:. Cost-Effectiveness Acceptability Curve for C-ADR Versus Fusion for One-Level Cervical Degenerative Disc Disease

Figure 10:. Cost-Effectiveness Acceptability Curve for C-ADR Versus Fusion for Two-Level Cervical Degenerative Disc Disease

Figure 11:. Model Schematic of Budget Impact